Many types of apparatus and processes have been suggested, and some utilized, for the movement, confinement, concentration and collection of unwanted floating substances and materials, such as oil spills. Most involve the technique of concentrating a wide shallow oil slick into a narrow deeper slick to enable a mobile collecting or recovery device, usually of the skimmer type, to pick up the oil in less time and with a greater oil to water ratio with resultingly increased efficiency. Exemplary of such suggestions, and some utilizations, are the disclosures of the following U.S. Pat. Nos. Mueller 3,659,713 May 2, 1972 Petersen et al 3,661,264 May 9, 1972 Bell 3,708,070 Jan. 2, 1973 Graham 3,762,169 Oct. 2, 1973 McGrew 4,033,869 July 5, 1977 Ogura et al 4,128,068 Dec. 5, 1978
Probably the most widely used of the suggestions advanced by the foregoing patents involves a mobile floating collection or recovery device equipped with a pair of forwardly diverging arms or booms, or their equivalent, for funneling unwanted floating substances into the forward end of the device as it sweeps the area where the substance is floating. In some, the arms are in the form of partially-submerged scoop-like wings or baffles. Exemplary of this construction is the disclosure of the above patent to Bell. This also discloses the use of jets of water on the upstream sides of the wings or baffles, some above and some below the surface of the water, angled generally toward the forward end of the collection device for assisting in concentrating and moving the floating substances into the collection device and to prevent an oil slick from moving over or under the wings or baffles in wave action. According to the above Petersen et al patent, one of the arms comprises the collection device itself, while the other arm is a log boom equipped with submerged nozzles for emitting underwater fan-shaped jets of water angled upwardly and toward the other arm or collecting device.
According to others of the above patents, i.e., Mueller and McGrew, the arms are disposed entirely above water and are equipped with nozzles for creating fan-shaped or continuous curtains of air or water jets to concentrate and move a floating substance into the collection device.
Lastly, the above listed Graham patent discloses the use of horizontal fan-shaped water jets at the water's surface for constrictionally surrounding an oil slick confined within a containment boom for concentrating and moving the slick into a collection device at one side of the boom.
All such systems, however, have disadvantages. The many and variously-angled water jets of Bell tend to mix floating oil with water, necessitating the handling of much more water by the collection device and thus greatly lowering its efficiency. The continuous fluid curtain of Mueller is, accordidng to the patent, preferably of air. If of water, the pumping requirements of the system, as is easily understood, would be economically almost prohibitive. Almost the same can be said of an air curtain because of the large requirements of power, weight and boat space for air compressors. The fluid curtains of Mueller and also the multiple variously-angled fan-shaped jets of McGrew tend to entrain water with the oil with the attendant same disadvantages as the Bell system.
The Petersen et al system has some one of the disadvantages of Bell, i.e., mixing of water with the oil. Moreover, it is doubtful that the Peterson system would be effective in a high current or in high wave action.
As far as the applicant is aware, the Graham system has not been used. It would be very cumbersome and require much effort to deploy.
As a matter of fact, none of the techniques disclosed in the above patents are actively used to control oil spills at the present time. Current practice is to use only floating barriers of booms, either solid or inflatable, to concentrate and control flow of an oil spill into a skimmer type of collecting device.